Hi from Your Friend's Architecture Blog! Today is another guest post; our second guest, in a hopefully re-occurring setup, on the blog. Mark Meiling is our guest expert today - he specializes in Home Performance. What is Home Performance you may ask? Well, it doesn't involve rehersals or stage presence... if that's what you were thinking. You probably weren't.. but I digress.
Mark is the president of ForeSight Home Performance. His independent private consulting services diagnose the cause of and design remedies for wet moldy attics, uneven heating/cooling, ice dams, window condensation from high relative humidity, smoky fireplace odors, and high energy use. He applies building science theory to analyze how well the integrated systems of a house work. Sophisticated diagnostic protocols are used with technically advanced equipment to evaluate these conditions. The collected data is used to drive the Scopes of Work he provides his clients. Projects are completed by private contractors with them working to the specifications and standards in his reports. This set of procedures provides his clients the assurance that the condition will be resolved with the work done once well. For more information about his background go to www.foresighthomeperformance.com
Wide shot, camera pans down, we enter the scene....
A week or so ago, my neighbor climbed into his attic to retrieve Christmas decorations. The Christmas tree and all the ornaments had water stains from water dripping from the roof decking above. Within the past couple of years he had a mold remediation company treat the attic side of roof decking with a white fungicide paint. They told him that the wet/moldy attic problem was solved. But the roof decking was dripping wet now! The paint was flaking and mold was found growing on the raw wood under the paint. He said “Grrrrr!”
The cause for this abnormal and harmful condensation event is water vapor traveling by air leaking from the living space into a cold unconditioned attic. Throughout every day we generate water vapor in our homes when we bathe, breath, cook and launder not to mention watering plants or running fish tanks. Attic ventilation was to code and functioning. The solution has nothing to do with attic ventilation. The volume of water vapor in living space air becomes too much for it to hold after this air enters a cold attic. When air cools it is less able to hold water vapor than when it is at room temperature. The vapor finds its way to the decking because it is at or below the dew point of the air leaking into the attic.
The remediation company telling my neighbor that they had solved the wet attic condition was a disservice. It would be like cleaning up the garage floor of an oil leak stain and thinking that the oil leak was fixed. The REAL way to solve this wet/moldy attic condition is about source control. Keep the source of the water vapor in the living space air from getting up into the attic. Simple, right?
Not so much. Holes in houses at exterior ceilings, walls and floors abound. They are found at major framing junctures, architectural features, plumbing/heating/electrical chases. They all provide pathway for air leakage. When building a new home, theoretically, it is easy to seal all of the holes because before the drywall goes up you can see all the holes that need sealing. But retrofitting requires a significantly greater level of difficulty. Mold remediators should never be counted on to solve an abnormal and harmful level of attic condensation. While many insulators have gotten basic air sealing training, few are master air sealers. And there are no designations for those whom could be considered master air sealers.
As a master air sealing technician the only way I’ve been able to KNOW when air leakage is under control, because air and water vapor are invisible, is to performance test building envelopes. In a perfect world, if I depressurize the air in the living space of a house with a pressure sensor in an attic, I should see no air pressure change in the attic. We don’t see perfectly tight houses in the real world. Not even new houses can be made perfectly air tight. Data driven performance testing to performance standards will determine when an air sealer has successfully completed their task in either a new or existing home.
Unfortunately Blower Door technicians able to perform tests to standards are few and far between. This is because the goal of the training provided these technicians has nothing to do with solving performance problems such as unevenly heated/cooled houses, wet/moldy attics, ice dams, window condensation, to mention just a few. The majority of contractors out there end up assembling buildings that get abnormal and harmful condensation which causes wet/moldy attics as well as an assortment of other issues.
For the time being, the best way to pick someone to direct an air sealer’s efforts is to find out whether they performance test to long established STANDARDS. Performance testing should include series air leakage, duct leakage, recessed light leakage, fan air flow and multi-zonal air pressure testing (concerning the impact of air pressure imbalances on combustion safety inside a home while running the forced air furnace with door closures). A technician who is capable of performing tests at this high level will more likely to be able to provide you with the peace of mind you deserve.
Wow - who knew there was so much to house performance. I guess the eternal battle will always rage - our buildings vs. Nature. They say, sure things in life are death and taxes, but now we all know you can include the great battle to keep nature from destroying your home to that list. Your Architecture Friend would like to thank Mark for all the technical knowledge he brings. As usual, please feel free to comment below, or drop me an email which I'll pass along to Mark (because I doubt I could answer your questions or figure out what is causing an issue!)